A number of proposals have hitherto been made with regard to this type of sliding material. For example, Japanese Patent Publications Nos. 2452/56 and 16950/64 disclose a hearing material having self lubricating property which includes a porous layer impregnated with polytetrafluoroethylene (hereinafter referred to as PTFE) or with an impregnating mixture consisting of PTFE, lead and/or lead oxide.
The known bearing material referred to hereinabove, however, has since become unsatisfactory in performance in view of the trend in the market that the load applied to the aforesaid sliding mechanism in which the bearing material is used is becoming increasingly higher.